// constructors
 public OdometerCorrection_v1(
     RobotCtrl robotCtrl,
     LineSensor lineSensorL,
     LineSensor lineSensorR,
     int odoCorrectionRefresh) {
   this.robotCtrl = robotCtrl;
   this.odometer = robotCtrl.getOdometer();
   this.lineSensorL = lineSensorL;
   this.lineSensorR = lineSensorR;
   this.odoCorrectionTimer = new Timer(odoCorrectionRefresh, this);
 }